Technical Abstract:
Pseudorabies virus (PRV) is a neurotropic alphaherpesvirus that produces fatal encephalitis in newborn pigs, respiratory disorders in fattening pigs and reproductive failure in sows. Infection of the respiratory tract by PRV, involves mononuclear cells in draining tracheobronchial lymph nodes (TBLN) which can enter the bloodstream resulting in restricted viremia. The objectives of this study were to determine innate immune cytokine profiles in tracheobronchial lymph nodes following experimental infection with PRV and compare the profiles to those of uninfected controls at 1, 3, 6 and 14 days post-infection (d.p.i.). Forty conventionally raised 4-5 week old pigs, free of clinical disease, were purchased from a PRV-negative herd. Twenty were inoculated with the Florida strain isolate (FS 268) of feral swine PRV and 20 control pigs were inoculated with spent media. In TBLN homogenates, protein expression levels of interferon (IFN) -alpha, interleukin (IL) -1beta, and IFN-gama were positively correlated with the severity of pulmonary pathology observed at 1 d.p.i. in the PRV infected pigs. There was also a significant inverse correlation between PRV infection in TBLN homogenates with the level of IL-18 protein expressed between 1 to 6 d.p.i. Examination of the immune response to infection with PRV has revealed important information about the porcine immune system.